The X-Files loomed large throughout the ’90s and early ’00s before reviving in 2016 for two seasons. It was a major win for sci-fi, with its influence still being felt today, both in the genre and beyond it. And at the center of its alien conspiracies and monsters-gone-rogue storylines were Mulder and Scully, the FBI’s “Most Unwanted” agents. The duo became a hot topic for their drawn-out will-they-won’t-they dynamic, fueled by underlying sexual tension in storylines and actors Gillian Anderson and David Duchovny’s innate chemistry.

Any fan of The X-Files knows the massive hype and anticipation surrounding Scully and Mulder’s relationship — no matter if they were for or against the once-controversial pairing. Audiences had to wait seven seasons for a kiss. After their relationship moved into official romantic territory, the next big question on everyone’s minds was when they would hook up. While creator Chris Carter was famous for limiting the duo’s intimate moments, he still threw them a bone on multiple occasions.

‘All Things’ Marked Scully & Mulder’s First Canonical Hookup

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Fans expecting a steamy sex scene between Mulder and Scully won’t find one in “All Things,” or anywhere in The X-Files, for that matter. However, the Season 7 episode opens with the implication that the agents spent the night together, with Scully leaving a naked Mulder asleep in bed after dressing herself in his bathroom. Gillian Anderson wrote and directed the episode, which is very much about fate and choices. According to IMDb, Anderson’s original draft of “All Things” was too long and had no fourth act. This generated some revisions from Carter and executive producer Frank Spotnitz, who included the ambiguous opening.

Chronologically within the episode timeline, the intro follows a sweet moment between the duo the night before that sees Mulder lovingly brushing a strand of hair out of Scully’s face and covering her with a blanket. It’s unclear exactly what transpired between the two scenes; however, it’s considered the first canon hookup between the two.

‘Trust No 1’ Confirmed Mulder & Scully’s Late Night Trysts

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Funnily enough, Scully and Mulder’s next hookup is confirmed in an episode sans Mulder after David Duchovny left the show in Season 8. Season 9, Episode 6, “Trust No 1,” sees Scully dealing with the National Security Agency and super-soldiers, all while attempting to arrange Mulder’s return. At the center of the episode is the Shadow Man, an NSA operative (later revealed as a super-solider) who admits he’s been spying on Scully for some unspecified amount of time. He knows everything about her, including her clothing size, blood type and childhood fear of clowns. While confronting her in person, the Shadow Man also drops a juicy bit of information: Scully and Mulder hooked up… again.

How he knows this is more than disturbing, as he explains to Scully that he essentially watched it happen, saying, “And I know that on one lonely night, you invited Mulder to your bed.” The reveal elicits tears and a look of shame from Scully, but she doesn’t shoot down the remark about sleeping with Mulder. Given the episode shows the Shadow Man has a video feed of her apartment, his authority on the matter remains reliable (and, of course, very creepy). While the comments in “Trust No 1” suggest another one-and-done encounter, who’s to say that Scully and Mulder didn’t have more nighttime rendezvous off-screen?

Season 11 Delivered The X-Files’ Most Explicit Scully & Mulder HookupsThe X-Files - Mulder and Scully Season 11 'Plus One'

The X-Files’ two-season revival was hit-or-miss among critics and fans alike, with its Cigarette Smoking Man/William twist leaving most audiences (and actor Gillian Anderson) unhappy. Still, there were a few standout episodes that transported the best aspects of the beloved show into the modern age. Among favorites like “Mulder and Scully Meet the Were-Monster” and “The Lost Art of Forehead Sweat” is Season 11, Episode 3, “Plus One.” While the actual storyline sees the agents investigating people being killed by their doubles, the most talked about part of the episode was Scully and Mulder sleeping together.

As the case takes its emotional toll on the pair, Scully ends up snuggling with Mulder in his motel bed. Although the camera pans away before fans can see any action, there is an obvious implication that the two have sex. In case viewers weren’t sure, Chris Carter delivered a bit of uncharacteristic explicitness, with Mulder waking Scully up in a panic during the night, urging her to “get dressed” and “put a dimmer on that afterglow.”

The episode’s conclusion also features another sexy interaction between the two. Mulder heads off to his adjoining motel room, telling Scully to call him if she needs anything. While Scully cooly insists that she won’t, she looks to the door after he leaves, smirks, and says, “But then again, it’s not out of the realm of extreme possibility.” When she opens the door, Mulder is waiting there with a grin, highly implying the two will be doing more of what transpired between them the night before.

While “Plus One” wasn’t the pair’s first journey down the hookup road, it was certainly the most obvious. News of the pair’s sexual exploits ignited The X-Files fan base, who had waited almost a quarter of a century to witness such a direct reference to the event. Gillian Anderson even got in on the fun by confirming Scully and Mulder’s double hookup via Twitter.

The X-Files Isn’t Short on Suggestive Mulder & Scully Encounters

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While there are only four (counting “Plus One’s” double whammy) canonical instances of Scully and Mulder sleeping together in the entirety of The X-Files’ 11 seasons, the series isn’t short on suggestive moments that tease something more x-rated is going on off-screen. Fans jokingly refer to Season 7 as the “Season of Secret Sex,” with the long-time partners becoming increasingly flirtatious and even kissing in Season 7, Episode 4, “Millennium.” “Hollywood A.D.” features Scully and Mulder bantering, watching a movie together and holding hands, implying the two may be dating. While “Hollywood A.D.” occurs after the duo’s first canonical hookup in “All Things,” some X-Files fans think their “couple status” could have started even earlier. Episodes like “The Goldberg Variation” and “Rush” only add fuel to these theories, with the pair much more playful and almost giddy around each other.

Perhaps more damning is Scully’s pregnancy storyline. Season 8, Episode 13, “Per Manum,” reveals Scully asked Mulder to be her doner while undergoing in vitro fertilization to combat the fertility issues caused by her abduction. While audiences later learn that IVF was unsuccessful via flashback, both Scully and Mulder have no doubts that Mulder is William’s father. Of course, this all changes in Season 11, when the Cigarette Smoking Man infamously confesses that he impregnated Scully with “science” during their road trip in Season 7’s “En Ami.” Still, it doesn’t change the fact that Mulder and Scully believed William was theirs until only moments before. And if the IVF failed, that implies they conceived the old fashion way.

Since the ’90s, Internet forums and fanfiction have been dedicated to answering the when and hows of Mulder and Scully’s love life. Carter and the writers left a lot to the imagination, and much of their dynamic is revealed in things that aren’t said out loud. In many ways, Scully and Mulder’s complicated and mysterious relationship is an X-File itself, one that fans will likely never entirely learn the truth of.